Low pressure, continuous flow fuel injection system



17959 c. M. ELLIOTT ETAL 2,871,844

LOW PRESSURE, CONTINUOUS FLOW FUEL INJECTION SYSTEM Filed Dec. :50, 1955 a Sheets-Shet 1 Feb. 3, 1959 C. M. ELLIOTT ET AL LOW PRESSURE, CONTINUOUS FLOW FUEL INJECTION SYSTEM Filed Dec. 50, 1955 5 Sheets-Sheet 2 Mid aZer? 7 6743421.

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c. M. ELLIOTT ET AL 2,871,844 LOW PRESSURE, CONTINUOUS FLOW FUEL INJECTIONISYSTEM Feb. 3, 1959 3 Sheets-Shet s V Filed Dec. 30, 1955 I m n? United States Patentv O f'ce LOW PRESSURE, CDNTINUOUS FLOW FUEL INJECTION SYSTEM Clifton M. Elliott, Birmingham, Robert P. Graham, Pontwo, and Mearl E. Noftz, Birmingham, Mich, assignors to Chrysler Corporation, Highland Park, Michu, a corporation of Delaware Application December 30, 1955, Serial No. 556,525 15 Claims. (Cl. 123-119) Our invention relates generally to a new and improved fuel injection system for a liquid fuel combustion engine, and more particularly to a low pressure fuel injection system of the continuous flow type.

The fuel system of our invention is particularly adapted to be used with internal combustion'engines for automotive vehicles although we contemplate that it may also be used with success with other types of power plants and other types of liquid fuel combustion appara- Our present invention comprises an improvement in the copending application of Jorma O. Sarto, Serial No. 460,668, filed October 6, 1954, and in our application Serial No. 504,577, filed April 28, 1955, now abandoned, said applications being assigned to the assignee of our instant invention.

The fuel system disclosed in theabove-mentioned copending applications is characterized by a plurality of air atomizing liquid fuel nozzles, each of which is adapted to be associated with one of the engine cylinders of the internal combustion engine for supplying the engine cylinders with a combustible charge of atomized fuel. The engine is provided with an air induction manifold comprising separate branch manifold conduits for each engine cylinder within each of which a manually controlled throttle valve is positioned, said throttle valves regulating the rate of delivery of combustible mixture to the engine cylinders. The air atomizing nozzle for each engine cylinder is mounted with the discharge portion thereof in the associated intake manifold branch conduiton the upstream side of the throttle valve. The various nozzles of the fuel system disclosed in the above-mentioned copending applications are supplied by means of a multiple branch delivery passage means or gallery wherein the main fuel passage portion communicates with a plurality of branch passages, each of the latter communicating with a separate nozzle. The main passage portion. communicates with the discharge side of the fuel supply pump through a fuel delivery passage defined in part by a fuel scheduling mechanism capable of regulating the rate of flow of fuel to the nozzles to a value which is proportional to the fuel demands of the engine. Fuel atomizing air may be supplied to each of the nozzles by means of a separate air pumping means, suitable air delivery passages being provided for this purpose.

The above-mentioned fuel scheduling mechanism comprises two principal portions which are referred to in the above-mentioned copending applications as a speed sensor unitand as a load sensor unit, the former being responsive to engine speed for regulating the rate of fuel delivery, and the latter being responsive to engine load for varying the fuel supply in accordance with variations in the load requirements of the engine. The speed sensor unit is comprised in part by a first fuel metering orifice located in the fuel delivery passage and an adjustable valve for regulating the degree of restriction of the orifice, said valve being connected to and I 2,871,844 Patented Feb. 3, 195? 2 adjustably positioned by a movable wall which is exposed on one side thereof to the fuel pressure existing on the downstream side of the first metering orifice. The'load sensor unit comprises a second fuel metering orifice situated in the fuel delivery conduit in series with the above-mentioned first metering orifice of the speed sensor unit, the degree of restriction of the second metering orifice being controlled by a movable valve which is adjustable with respect to the orifice in response to variations in the intake manifold vacuum pressure of the engine. side of the movable wall to the fuel pressure existing on the downstream side of the load sensor unit thereby making thespeed sensor sensitive to pressure variations in the downstream portion of the fuel circuit.- The speed sensor responds to suchpressure variations and makes appropriate adjustments in the speed sensor valve to maintain a uniform rate of fuel delivery in spite of the change in pressure.

The above-mentioned main fuel passage portion of the distribution gallery communicates with the downstream side of the second fuel metering orifice and forms a continuation of the fuel delivery passage. Thepressure on the downstream side of the second metering orifice is transmitted to the other side of the movable wall of the speed sensor unit thereby causing the pressure differential across the movable wall to be equal to the pressure differential across the second metering orifice.

During idle and low speed operation of the engine, the pressure differential across the first metering orifice is relatively large in value and a tendency exists for fuel vapor to be created in the fuel delivery passages especially when the engine operating temperatures are high. The presence of fuel vapor in the fuel delivery passages causes erratic operation of the load sensor unit and of the nozzles which in turn results. in undesirable engine performance. Further, since the branch fuel passages for each of the nozzles communicate with themain passage portion at separate locations, any vapor which exists in the fuel delivery passages will be unevenly distributed to the various nozzles so that at any given time it is quite possible that one nozzle will function differently than another. Also, the operation of each of the individual nozzles will be sporadic and unpredictable in nature since the nozzle characteristics for any given nozzle is dependent upon whether or not fuel vapor is distributed to its associated branch fuel passage.

According to a principal feature of our instant invention, we have eliminated those problemsassociated with this fuel vaporizing condition thereby adapting the system for a wide variety of operating conditions.

The provision of an improved fuel metering system of the type above described being a principal object of our invention, it is a further object of our invention to provide a fuel regulating mechanism having a load sensor unit and a speed sensor unit of the type above described wherein means are provided for purging the fuel vapor from. the portion of the fuel delivery passage on the downstream side-of the speed sensor metering orifice before the fuel reaches the metering orificeassociated with the load sensor unit.

It is another object of our invention to provide a fuel system of the type set forth in the preceding object wherein a portion of the fuel passing through the metering orifice of the speed sensor unit may be bypassed to a fuel supply .tank situated on the intake side of the fuel delivery pump, the remaining portion of the fuel passing through the second metering orifice of the load sensor unit as above described.

It is another object of our invention to provide a new. and improved fuel delivery conduit system interconnecting Passages are provided for subjecting the other' the speed sensor unit of a system of the type above described with each of the air atomizing nozzles associated with the individual engine cylinders, a separate delivery passage being provided for each nozzle.

It is another object of our invention to provide a fuel distributing system of the type set forth in' the preceding object wherein the individual delivery passages for each nozzle communicate with the load sensor unit on the downstream side of the load sensor metering orifice at a common location.

It is another object of our invention to provide a fuel regulating system of the type above described wherein valve means are disposed within the bypass means for regulating the rate at which fuel is bypassed around the load sensor unit, the flow of fuel through the bypass valve means being inversely proportional in magnitude to the engine fuel requirements.

It is another object of'our invention to provide a load sensor unit for use in the system above described wherein means are included for varying the rate of delivery of fuel to the air atomizing nozzles in accordance with the engine requirements for any given load.

For the purpose of particularly describing the principal features of our invention, reference will be made to the accompanying drawings wherein: a

Figure l is a schematic representation of the fuel system of our instant invention showing the load sensor, the speed sensor, the air atomizing nozzles and the associated conduit structure;

Figure 2 is a cross sectional view of an actual working embodiment of the fuel regulating mechanism of the system of our instant invention;

Figure 3 is a cross sectional view of the air pumping unit capable of supplying the nozzles with fuel atomizing air;

Figure 4 is a detail cross sectional view of an air atomizing nozzle for one of the engine cylinders; and

Figure 5 shows portions of the engine intake manifold conduit together with the conduit structure for obtaining a vacuum signal for the load sensor unit and for the speed sensor unit.

Referring first to Figure l, the engine is generally designated by numeral and it includes a plurality of engine cylinders which are supplied with intake air through an induction manifold having branch portions 12, one of said branch portions communicating with each engine cylinder. A plurality of air atomizing nozzles are designated by numeral 14 and are connected to a load sensor unit 16 of the fuel metering system by means of individual distribution passages 18, one passage 18 extending to each nozzle 14. Each of the nozzles 14 is in turn mounted within one of the intake manifold portions 12, Figure 4.

The load sensor unit 16 includes a distribution chamber 20 to which each of the passages 18 extends and it is defined in part by a wall having a metering orifice 22 formed therein. A passage 24 interconnects the load sensor unit 16 with a speed sensor unit generally designated by numeral 26, the passage 24 and the passages 18 being situated on opposite sides of the orifice 22. The speed sensor unit 26 is divided into four principal chambers by three movable walls 28, 30 and 32 which are centrally connected to a common coupling shaft 34. Centrifugal governor means 35 are housed by a portion of the speed sponsor unit 26 and it includes portions adapted to adjustably position the shaft 34, the rotary portion of said governor means being driveably connected to the vehicle engine crankshaft.

The passage 24 communicates with a fuel chamber 36 defined in part by the movable wall 28 and a fiow metering orifice 38 provides communication between the chamber 36 and a fuel delivery conduit 40. The degree of restriction of the metering orifice 38 is controlled by a movable valve element 42 which may be adjustably positioned by the shaft 34 as the latter is adjusted by the abovementioned governor means 35. The fuel delivery conduit 40 is supplied with fuel by a fuel pumping unit 42 which may be an electrically driven pump'or which may be powered by the vehicle engine, the intake side of the pump 42 communicating with a fuel supply tank 44. A suitable filter 46 may be interposed between the pump 42 and the speed sensor unit 26 as indicated.

A relief valve controlled bypass passage 50 may extend from the discharge side of the pump 42 to the low pressure supply tank 44 for bypassing that portion of the pumped fuel which is not utilized by the fuel regulating system. A relief valve 52 is interposed in the bypass line 50 for the purpose of maintaining a substantially constant pressure differential across the fuel pump 42.

Referring again to the speed sensor unit 26, the movable walls 28 and 30 define a second fuel chamber 54 which communicates with the load sensor unit 16 on the downstream side of the load sensor metering orilce 22 by means of a passage 56 and the pressure differential exlsting across the metering orifice 22 is thereby applied to opposite sides of the movable wall 28.

A third chamber 58 is defined by the movable walls 30 and 32 of the speed sensor unit 26 and it communicates with one or more of the intake manifold branch portions 12 through a vacuum pressure passage 60, said passage 60 being connected to the individual manifold branch portions 12 in the vicinity of the throttle valve elements 61. It is contemplated that the connection between the manifold branch portions 12 and the passage 60 will be located directly adjacent the edge of the throttle valve 61 when the latter assumes a closed position as indicated schematically in Figure 1. By preference, an air chamber 62 is situated in the vacuum pressure passage 60 and it communicates at one end thereof with the passage 60 through a restricting orifice 64. An air bleed 66 may be provided as indicated.

To facilitate starting, we have provided a starting bypass passage 68 having a control valve 70 .situated therein for controlling the rate of flow through the bypass passage 68 toa value which is sufficient to initiate combustion and to accelerate the engine up to an idling speed. The flow of fuel through the bypass passage 68 supplements that which is metered'through the speed sensor metering orifice 38. A check valve .48 is interposed in passage 68 between the valve 70 and the passage 24 to prevent a reverse flow of fuelfrom passage 24.

Referring again to the load sensor unit 16, the metering orifice 22 is controlled by an adjustable needle 72 which is carried by a piston or a movable wall 74, the latter being spring biased toward an orifice opening positioned by the spring 76. A vacuum pressure signal may be applied to the load s'ensorunit 16 through a vacuum pressure passage 78 which communicates with a plurality of branch passages 80 extending to each intake manifold branch portion 12. The individual branch passages 80 communicate with each branch manifold portion 12 on the downstream side of' the associated throttle valve 61 thereby causing a negative pressure to be transmitted to the upper side of the piston 74 of theload sensor unit 16.

An accelerator pumping mechanism is generally designated in Figure 1 by numeral 82 and it comprises a cylinder 84 within which is slidably disposed a working piston 86. The piston 86 may be connected to the throttle linkage mechanism so that it will move in a downward direction during acceleration of the vehicle. The working chamber Within the cylinder 8.4 below the piston.86 communicates with the low pressure bypass passage 68 on the upstream side ofvalve 48 through a passage 88. An accelerator pump delivery passage 92 interconnects'the distribution chamber 20 of the load sensor unit 16 with the above-mentioned working chamber of the accelerator pumping mechanism 82 to accommodate the delivery of an auxiliary charge of fuel to the nozzle 14 upon movement of the piston 86 in a downward direction. A suit- 3 able one-way check valve 94 is provided for controlling the delivery of fuel through the passage 92.

A bypass passage 96 interconnects the load sensor unit 16 with the low pressure tank 44 for bypassing a substantial portion of the fuel delivered to the load sensor unit 16 by the passage 24. The bypass passage 96 communicates with the interior of the load sensor unit 16 on the upstream side of the metering orifice 22 and the rate of flow of bypass fuel therethrough is controlled by a flow control valve generally designated in Figure 1 by numeral 98, said valve 98 reducing the rate of bypass flow as the fuel pressure in the load sensor unit increases and increasing the rate of bypass flow as the fuel pressure decreases.

A bleed line extends from the working chamber of the pumping mechanism 82 to the bypass line 96 and a flow restricting orifice 97 is situated therein as indicated.

Atomizin-g air may be supplied to the nozzles 14 by means of an air pump generally designated by numeral 100 and an air delivery passage 102, said passage 102 communicating with a plurality of branch air passages 104 for each of the nozzles 14. Air may be supplied to the intake side of the pump 100 through intake air passages 106 and 108, the latter also serving as a vent for the chamber situated below the piston 74 of the load sensor unit 16.

Referring next to Figure 2, the load sensor unit and the speed sensor unit above described are shown as part of a single compact assembly which includes four principal housing sections identified separately by numerals 110, 112, 114 and 116. The above-mentioned speed governor means 35 is housed within the section 110 and it includes an engine driven shaft 118 journalled by bearings 120 within a hollow extension 122 of the section 110. -The shaft 118 carries amounting bracket 124 on which is pivoted a pair of centrifugal weights 126. The weights 126 are adapted to engage a sleeve 128 slidably carried by an extension 130 of the shaft 118 and as the weights are rotated about the axis of the shaft 118 they tend to pivot counterclockwise, as viewed in Figure 2, thereby urging the sleeve 128 in a right hand direction with a force which is substantially proportional to the square of the speed of rotation of the shaft 118.

The housing section 110 is secured to the adjacent section 112 by bolts 132. A circular member 134 is secured to the housing section 112 at a radially inward location and the above-described flexible diaphragms 30 is disposed between the juxtaposed surfaces of the housing section 112 and the circular member 134. A second circular member 138 is positioned adjacent the member .134 and the above-mentioned flexible diaphragm 32 is interposed between the juxtaposed surfaces of the members 134 and 138 as indicated. A clamping bolt 142 is provided for maintaining the members 134 and 138 and the housinng section 112 in clamping engagement. The flexible diaphragms 30 and 32 extend transversely across a central recess 144 formed in the housing section 112 and across central openings 146 and 148 formed in the circular members 134 and 138 respectively, thereby defining separate chambers 150, 58, and 154, the latter being coextensive with the enclosure defined by the housing section 110 for the speed governor means 35. The chamber 58 was previously described in connection with the schematic drawing of Figure 1 and it communicates with the above described vacuum pressure passage 60 by means of an internal conduit 156 extending through the housing section 112 and the circular member 134. The effective diameter of the diaphragm 32 is substantially greater than the effective diameter of the diaphragm 30 for reasons which will subsequently become apparent.

Another recess 158 is formed on the opposite side of the housing section 112 thereby defining the abovementioned chamber 54, and the above-described diaphragm 28 is disposed thereacross as indicated, the periphery of the diaphragm 28 being clamped between the juxtaposed surfaces of the adjacent housing sections 112 and 114.

- The diaphragms 32, 30 and 28 are coupled together for simultaneous movement by a multiple piece coupling shaft comprising sections 160, 162 and 164, said sections being held in clamping engagement by means of a threaded connection between the center section 162 and each of the adjacent sections and 164. The central portions of the diaphragms 32 and 30 are clamped between clamping plates 166 and 168 respectively. The center portion of the diaphragm 28 is secured to the shaft section 164 by means of clamping plates 170 secured at the end thereof by a clamping screw 172.

The housing section 114 is formed with a recess 174 which defines the above-mentioned chamber 36 and a threaded opening 176 is formed in the housing section 114 with one end thereof communicating with the chamber 36 and the other end thereof communicating with a transverse opening 178 formed in the housing section 114. A sleeve 180 is threadably received in the opening 176 and the above-mentioned fuel metering orifice 38 is formed at one end thereof as indicated. The metering valve element 42 is slidably positioned within the sleeve 180 and is spring biased in a left hand direction as viewed in Figure 2 by a spring 182. The valve element 42 is formed with a tapered metering portion 184 and an extension 186 extending through the orifice 38 and engaging clamping screw 172 of the coupled diaphragms.

The above-mentioned starting control valve 70 includes a valve sleeve 188 which is positioned within the opening 178 and retained therein by a suitable threaded connection 190, this portion of the fuel metering structure being indicated in Figure 2 in a plane which is offset from the cross sectional plane of the other portions of the mechanism. The sleeve 188 is hollow and is adapted to slidably receive a spool valve element 192 having a central reduced diameter section 194. The valve element 192 is biased in a downward direction, as viewed in Figure 2, by a spring 196. An annular groove 198 is disposed about the sleeve 188 and it communicates with the interior thereof through ports 200. The interior of the sleeve 180 and the fuel delivery passage 40 communicate with the groove 198, as indicated, to provide a through passage between the orifice 38 and the exterior portion of the fuel delivery passage 40, a suitable fluid fitting 202 being provided, as shown, to connect the passage 40 with the housing section 114.

The interior of the valve sleeve 188 surrounding the reduced diameter section 194 of the spool valve element 192 communicates with the lower portion of the opening 178 through one or more ports 204 which are progressively restricted by the spool valve element 192 as the latter movesin an upward direction from the lowermost position defined by a stop 206. The opening 178 commu nicates with the above-mentioned passage 68 which extends to the fluid chamber 36 on one side of the flexible diaphragm 28. A manually adjustable valve 208 is situated within the passage 68 to provide a controlled restriction of the same.

Referring next to the load sensor 16 situated on top of the assembly as viewed in Figure 2, an adaptor is designated by numeral 210 and it is formed with a downwardly extending portion 212 situated within an opening 214 formed in the housing section 114. The lower portion of the opening 214 communicates with the fluid chamber 36 through the fluid passage 24, as previously described. The above-mentioned distributing chamber 20; is formed within the extension 212 and it communicates: with the lower portion of the opening 214 through theorifice 22. The distributing chamber 20 further communicates with the fluid chamber 54 on one side of the flexible diaphragm 28 through the above-mentioned pas sage 56 which is formed in the housing sections 112 and. 114 and which is defined in part by a port 216 and by acommunicating groove 218 formed in the adaptor extension 212.

The upper part of the adaptor 210 receives a plurality of tubes 220 threadably received within openings formed in a circular row about the axis of the adaptor 210 thereby defining a structure somewhat resembling a rosette. A separate one of the above-mentioned nozzle delivery passages 18 is connected to each of the tubes 220 by means of a suitable fitting 222. By preference the passages 18 are formed of some suitable material which is relatively non-conductive of heat.

The upper portion of the adaptor 210 threadably carries the housing section 116 of the load sensor 16 and the piston 74 is slidably received in the housing section 116 as indicated. The metering pin 72 is carried by the piston 74 and it includes a tapered section 224 extending through the orifice 22. The upper portion of the adaptor 210 suitably pilots the metering pin 72 during movement thereof in an upward and downward direction as viewed in Figure 2.

An end cap 226 may be provided on the housing sec- .tion 116 thereby defining an enclosed passage chamber 228 within which is situated the spring 76. The chamber 228 communicates with the vacuum pressure passage 78 as above described, a suitable fitting 230 being provided for this purpose.

It will be apparent from an inspection of Figure 2 that the metering pin 72 will variably restrict the fuel metering orifice 22 in response to variations in engine manifold vacuum, the higher the vacuum, the greater the degree of restriction. However, since the engine load does not vary linearly with engine manifold vacuum, it is necessary to provide a second spring as shown at 76' within the chamber 228 for urging the same in a downward direction.

When the metering pin 72 is moved to a fully open position, the spring "16 will be unseated and the spring 76' will exert a downward force to oppose the vacuum pressure existing in the chamber 228 under these conditions and to resist initial movement of the piston 74 from its extreme downward position. As the vacuum increases in magnitude, the piston 74 will be raised vertically thereby tending to restrict the orifice 22, and at some predetermined location the second spring 76 will become seated and any further upward movement of the piston 74 will be opposed by the forces exerted by each of the springs 76 and 76'. combined springs 76 and 76' therefore varies from one value to another during movement of the piston from one extreme operating position to the other.

The above-described flow control valve 98 comprises a valve sleeve 232 joined to the housing section 13.4 and it contains a movable valve element 234 which registers with a flow metering orifice 2.36. The valve element 234 is biased in a valve opening position by a spring 238. The interior of the sleeve 232 communicates with the above-mentioned bypass passage 96 on one side of the orifice 236. Part of the passage 96 is defined by an internal passage 96' within the housing section 114 which interconnects the interior of the sleeve 232 with the opening 214 on the upstream side of the load sensor orifice 22.

The valve element 234 includes a piston-like section 240 which is formed with peripheral openings 242 to permit the passage of bypass fiuid through the sleeve 232 and into the bypass passage 96 on the downstream side of the orifice 236. As the pressure within the chamber 214 increases due to an increase in the engine fuel requirements, the valve element 234 will be urged to the right thereby restricting the orifice 236 which in turn reduces the rate of flow of fuel through the bypass passage 96. It therefore follows that the percentage of fuel which is utilized by the engine increases in direct proportion to the amount of the decrease in the bypass flow.

The above-described accelerator pumping mechanism 82 may comprise a separate housing section 244 secured to the housing section 114 which defines the above-men- The effective spring rate for the tioned cylindrical opening 84. The piston 86 preferably comprises a reentrant type, flexible, non-sliding diaphragm 246 and a circular, cup-shaped piston 248 carried by a piston rod 250. The piston rod 250 in turn comprises a portion of the accelerator linkage mechanism.

Referring next to Figure 3, we have illustrated one type of air pumping mechanism which may be employed for the purpose of obtaining a constant supply of fuel atomizing air for the various nozzles 14. This pumping mechanism is of the double acting type and it may comprise two principal housing portions 252 and 254 between which is positioned a pumping diaphragm 256. The first housing section 252 defines an upper working chamber 258 which receives an air spring 260 for normally biasing the diaphragm 256 in a downward direction. Similarly, the other housing section 254 defines a working chamber 262 below the diaphragm 256 and it is formed with an inlet check valve generally designated by numeral 264, said check valve communicating with a similar check valve 266 for the upper chamber 258 through internal passages 268 and 270 formed in the housing sections 264 and 262 respectively. The inlet check valves 264 and 266 communicate with the common air inlet passage above described with reference to Figure 1 through an inlet opening 270.

The working chambers 258 and 262 are further provided with outlet check valves generally designated by numerals 272 and 274 respectively, and they in turn communicate with the above-described common air delivery passage 102 by means of interconnecting internal passages 276 and 278 respectively.

The central portion of diaphragm 256 is secured to diaphragm actuating shaft 280 by means of a connection which includes backup plates 282 and 284, said shaft 280 extending through a pilot bearing 286 positioned in a central opening 288 in the housing section 254. A suitable shaft seal for the shaft 280 may be provided as indicated at 290.

The lower portion of the housing section 254 is recessed to receive a rocker arm 292 which engages the shaft 280 and urges the same in an upward direction, as viewed in Figure 3, as it is moved in a clockwise direction about the pivot point 294. We contemplate that a suitable cam arrangement may be provided for driveably connecting the engine crankshaft with the rocker arm 292 to effect an oscillating motion of the latter. It is thus apparent that the air pump is double acting and that an oscillatory movement of the arm 292 will be accompanied by a reciprocating movement of the shaft 280. The air displaced by the diaphragm 256 will be alternately delivered through the outlet check valves when associated with each working chamber 258 and 262 to the nozzles 14, and the pumped air is replaced during the return movement of the diaphragm 256 by air entering the inlet check valves.

Referring next to Figure 4, one type of air atomizing nozzle 14 which has been successfully used in the system herein described comprises a main body portion 296 which may be fitted within a suitable nozzle opening 298 in the wall of the intake manifold branch portion 12 on the upstream side of one of each of the throttle valves. The body portion 296 includes an externally threaded fitting 300 over which is received a retainer cap 302 for securing the end of the fuel delivery passage 18 to the body 296. A central fuel passage 304 is formed in the body portion 296 and communicates with the abovementioned fuel delivery passage 18. A swirl chamber 306 is formed at the terminal portion of the body 296 and it communicates with the central passage 304 through a nozzle orifice 308. An annular air chamber identified by numeral 310 is formed about the exterior of the body portion 296 and the surrounding wall of the opening 298 and it communicates with the swirl chamber 306 through tangentially directed ports 312. The abovementioned air delivery passage 102 and the branch air Q passages 104 communicate with the air chamber 310 for each nozzle 14 through ports not specifically shown in Figure 4.

In operation, fuel is delivered through the central passage 304 and it is mixed with atomizing air in the swirl chamber 306 as it passes the nozzle orifice 308, said atomizing air entering the swirl chamber 306 with a tangential velocity which breaks up the fuel into small particles before it is ejected outwardly from the swirl chamber 306 into the intake manifold branch portions 12 for each engine cylinder.

Referring next to Figure 5, a portion of the intake manifold branch portions 12 is shown in more particular detail and the relationship between the throttle valve 61 and the location of the passages 80 and 60 may be observed.

When the fuel system above described is in operation the fuel pump delivers fuel through the fuel delivery passage and through the speed sensor metering orifice into the fuel chamber on the downstream side of the metering orifice and then through the load sensor metering orifice into the distributing chamber from which the fuel is transmitted through the individual delivery passages for each of the air atomizing nozzles. The speed sensor orifice and the load sensor orifice are situated in series and any change in the degree of restriction of either of the orifices will cause an appropriate change in the rate of fuel delivery to the nozzles. The speed sensor metering element is adjustable with respect to its associated metering orifice by the above-described governor means which may be powered by the vehicle engine. It will be apparent that a change in the speed of rotation of the rotary portions of the governor means will cause the sleeve .128 to shift thereby causing a corresponding adjustment in the speed sensor diaphragms and the diaphragm coupling shaft with which the sleeve 128 is in contact. Adjustment of the speed sensor diaphragms is accompanied by a corresponding movement of the speed sensor metering element thereby varying the degree of restriction of the speed sensor metering orifice.

Similarly, the manifold vacuum signal which is applied to the load sensor unit will cause an adjustment in the position of the load sensor metering element with respect to the load sensor metering orifice, with the higher vacuum signal corresponding to the greatest degree of restriction of the load sensor metering orifice.

The pressure drop across the load sensor metering orifice will be transmitted across the speed sensor diaphragm thereby making the speed sensor sensitive to pressure variations in the fuel circuit on the downstream side of the load metering orifice as well as to pressure changes in that portion of the circuit intermediate the load sensor and speed sensor orifices. The load sensor unit and the speed sensor unit thereof cooperate and function simultaneously to provide a controlled supply of fuel to the air atomizing nozzles at a rate which corresponds to the engine demands under any operating conditions. If it is assumed, for example, that the engine load increases while the engine speed remains constant, an appropriate adjustment will be made in the setting of the load sensor metering element by reason of the accompanying reduction in magnitude of vacuum signal applied to the load sensor. This causes an increase in the effective size of the load sensor metering orifice which permits a greater fuel delivery rate. Since such an adjustment of the load sensor metering element would normally tend to cause a decrease in the pressure difierential across the load sensor metering orifice, and since this same pressure differential is transmitted to the opposed sides of the speed sensor diaphragm, an appropriate adjustment in the setting of the speed sensor metering orifice will takeplace. In other words, an increase in pressure on the downstream side of the load sensor orifice with respect to the pressure on the upstream side thereof will be transmitted to the speed sensor unit thereby urging the speed sensor diai t) phragm and the speed sensor metering element to a more fully open position. This in turn tends to increase the pressure on the upstream side of the load sensor orifice and on the downstream side of the speed sensor orifice. The pressure differential across the speed sensor diaphragm, when it assumes this new position, will therefore be the same as that which existed immediately prior to the above-mentioned change in engine load. Similarly, the pressure drop across the load sensor metering orifice will also remainunchanged although the rate of flow theretnrough will be increased in order to meet the increased engine fuel demands.

The contour of the load sensor metering element must be accurately calibrated in order that this characteristic might exist. The actual contour of the metering element which is most suitably for any given engine is dependent upon the relationshipbetween engine manifold vacuum and fuel flow.

It is emphasized that the net force acting on the adjustable portions of the speed sensor unit remain unchanged although the diaphragms and the metering element of the speed sensor unit have assumed a new setting by reason of the above-described change in engine load at a constant engine speed. In order that this condition might exist, it is necessary for the characteristics of the governor means to be such that the axial force exerted thereby on the coupled diaphragms is independent of the radial position of the centrifugal weights 126. The axial force exerted by the governor mechanism is balanced by a hydraulic force which exists by reason of the pressure differential across the speed sensor diaphragm and it is a function only of governor speed.

By way of further illustration, if the engine speed should vary while the engine load remains constant, an appropriate adjustment will be made in the setting of the speed sensor metering element as above indicated. If it is assumed that the speed is increased under constant load conditions, the speed sensor metering element will be shifted to a more fully open position thereby allowing an increase in the rate of fuel flow through the speed sensor metering orifice and. through the load sensor metering orifice to the various nozzles. This increased rate of fuel delivery which is necessary in order to meet the corresponding increased fuel demands of the engine will be accompanied by an increase in the back pressure on the upstream side of the nozzles, but since the fuel chamber on the downstream side of the speed sensor diaphragm is in communication with the downstream portion of the fuel circuit, the increased back pressure will tend to restore the pressure balance and to urge the speed sensor metering element to a more fully open position thereby compensating for the tendency of the increased back pressure to reduce the rate at which the fuel is metered past the speed sensor metering orifice. It is thus apparent that the speed sensor unit is sensitive to any variation in pressure on the downstream side of the speed sensor metering orifice and is capable of making automatic adjustments in the speed sensor metering element to maintain a constant rate of fuel delivery. Therefore, the change in the rate of delivery of fuel which accompanies a change in speed is a function only of engine speed. For example, if one of the nozzles should become fouled for some reason or if a portion of the fuel delivery passages should become clogged or otherwise constricted, the accompanying change in back pressure will cause the speed sensor metering orifice to assume a more fully open position thereby decreasing the degree of restriction of the speed sensor orifice to maintain a constant total fuel delivery to'the remaining nozzles and to the unrestricted passage portions on the downstream side of the circuit.

During starting operation the speed sensor metering element assumes a fully closed position and the starting control valve mechanism 70 is effective to cause a flow of fuel around the speed sensor orifice to facilitate starting,

the path of the bypass flow being defined in part by the ports 204 and by the passage 68. After the engine accelerates, the governor mechanism adjusts the metering element for the speed sensor to an appropriate idling position and the pressure on the upstream side of the speed sensor diaphragm increases. This increase in pressure is transmitted to the spool valve element 192 thereby urging the latter in an upward direction, as viewed in Figure 2, to restrict the bypass ports 204. This valve arrangement is capable of providing a bypass flow which varies in magnitude throughout a relatively large range of values without an accompanying change in pressure. Accordingly the valve mechanism 70 functions as a flow control valve capable of supplying the system with starting fuel at that rate which is required to initiate combustion and to facilitate acceleration of the engine while at the same time maintaining a constant fuel delivery pressure.

The biasing effort of the governor means is proportional to the square of the engine speed throughout the operating speed range of the engine. However, at relatively low' engine speeds the friction forces in the speed sensor mechanism represent a significant proportion of the total force which balances the centrifugal force created by the rotatably mounted weights 126. The net effective force acting on the speed sensor diaphragms therefore tends to deviate from the above-mentioned square law relationship at the lower engine speeds and for this reason provision is made for applying an auxiliary pressure force to the diaphragm coupling shaft. This auxiliary force is accomplished by reason of the differential in area between the diaphragrns 30 and 32 of the speed sensor unit. As vacuum pressure is applied to the chamber defined by the diaphragms 30 and 32, an axial force is applied to the diaphragm coupling shaft which supplements the biasing force of the centrifugal governor mechanism since the pressure force acting on the larger diaphragm is greater than the opposing force acting on the smaller diaphragm 30. The vacuum signal applied to the chamber defined by the diaphragms 30 and 32 is obtained by means of the associated vacuum pressure passage 60 connected to the intake manifold branch portion 12. The passage 60 communicates with the interior of the'manifold portion 12 through a port located directly adjacent a throttle valve 61 when the latter is in a closed position as viewed in Figures l and 5. As the throttle valve 61 approaches a fully closed position, the increased velocity of the intake air about the periphery of the throttle valve causes a reduction in the static pressure in the passage 60 and in the chamber between the speed sensor diaphragms 30 and 32.

A portion of the fuel passing through the speed sensor meterin orifice is bypassed through the bypass passage 96 before it reaches the load sensor metering orifice and is returned to the fuel tank thereby providing a constant circulation of fuel through the system in excess of that which is utilized by the engine. When the fuel requirements of the engine are at a reduced value, the rate of fuel delivery is correspondingly reduced and a larger percentage of the fuel metered by the speed sensor unit is bypassed directly to the tank while only a minor portion thereof is metered through the load sensor metering orifice. For example, with a typical automotive type internal combustion engine, the idling fuel flow rate through the speed sensor unit may be approximately 30 lbs. per hour, whereas only lbs. per hour are metered through the load sensor metering orifice, the remaining lbs. per hour being bypassed through the bypass passage 96 to the low pressure fuel tank.

As the fuel. requirements of the engine increase, the fuel pressure on the upstream side of the load sensor metering orifice will increase thereby causing an increase in the rate at which fuel is metered through the load sensor. Also, the rate at which fuel is bypassed through the bypass passage 96 is correspondingly decreased by reason of the operation of the bypass valve 98. The valve element 234 is exposed to this increased pressure on the upstream side of the load sensor metering orifice and is biased against the 12 opposing spring effort of the spring 238 thereby progressively restricting the passage of fuel through associated orifice 236. As a further example, if a typical internal combustion engine is operated at wide open throttle at 4,000 R. P. M., the total fuel requirements may be as large as lbs. per hour and the amount of this total flow which is bypassed through the bypass passage 96 may be negligible, substantially the entire flow being metered through the load sensor orifice.

The fuel pump, together with the valve controlled bypass, is capable of maintaining a substantially constant fuel delivery pressure, a typical value for the same being 30 p. s. i. g. During idling operation the pressure drop across the speed sensor metering orifice may be only slightly less than 30 p. s. i. g. so that the fuel pressure existing on the downstream side of the speed sensor orifice will be of a relatively negligible value, for example .7 p. s. i. g. A tendency exists for vapor to be created under such conditions on the downstream side of the speed sensor metering orifice by reason of this sudden drop in fuel pressure especially when the ambient air temperatures increase to those values which are typical for engine installations of this type. However, the percentage of the fuel flow which is bypassed under such conditions is relatively high in magnitude as above explained, and this causes the system to be purged of fuel vapor before it has an opportunity to pass through the load sensor unit. The additional flow of fuel through the system which takes place by reason of the above-mentioned bypass feature also tends to maintain the fuel in the circuit at a cooler temperature than that which would otherwise exist since a large portion of the heat absorbed by the fuel in passing through the system is circulated back to the fuel tank with the bypass fuel and is dissipated before vaporization of the fuel results.

Under certain operating conditions it is possible that the drop in the fuel pressure across the load sensor metering orifice might be relatively large in magnitude and this condition might also encourage the above-described fuel vaporizing condition although the problem is probably somewhat less severe in this portion of the circuit. As a typical example, if the engine is operated at closed throttle and at a speed of approximately 4,000 R. l. M. the fuel pressure on the upstream side of the speed sensor orifice will be approximately 30 p. s. i. g. as above indicated, the fuel pressure on the downstream side of the speed sensor orifice may be approximately 13 p. s. i. g. and the pressure on the downstream side of the load sensor orifice may be approximately one p. s. i. g., the pressure drop across the load sensor orifice therefore being 12 p. s. i. g. Any fuel vapor which is created by reason of this 12 p. s. i. g. pressure drop will be evenly distributed through each of the individual fuel delivery passages extending to the various air atomizing nozzles by reason of the common connection between the ends of the passages 18 with the distributing chamber 20. Such a uniform distribution of vapor will result in uniform operation of each nozzle and the amount of vapor transmitted to any given nozzle will be relatively slight in quantity. Further, the passages 18 may be conveniently located in a relatively cool part of the engine installation thereby retarding any vapor-forming tendency of the metered fuel. By preference the passages 18 may be formed of suitable material of low heat conductivity. By way of contrast, if fuel is transmitted from the metering mechanism to the air atomizing nozzles through a gallery-type distribution conduit system, the fuel vapor may collect in a common fuel passage portion and may be distributed unevenly to the various branch portions of the conduit system extending to the individual nozzles. Further, the common portion of the gallery must necessarily be located in a relatively high temperature section of the engine installation because of the requirement that it be situated relatively close to the engine cylinders.

Having thus described a preferred embodiment of our 13 improved fuel injection System, What We claim'and desire to secure by United States Letters Patent is:

l. A liquid fuel metering system comprlslng a fuel delivery passage defined in part by a pair of fuel metering orifices, a bypass passage extending from said delivery passage at a point intermediate the metering orifices to the upstream side of the orifices, and a valve means for controlling the rate of bypass flow, said valve means 1ncluding a first valve element, a valve port formed 1n sa1d first valve element and defining a portion of sa1d bypass passage, and a second valve element slidablydlsposed with respect to said first valve element, said second valve element being responsive to fuel pressure dilferentialthereacross to progressively vary the degree of restrict1on of said port to the flow of bypass fuel therethrough.

2. A liquid fuel metering system comprising a fuel delivery passage defined in part by a pair of fuel meterlng orifices, and a bypass passage extending from said delivery passage at a point intermediate the metering orifices to the upstream side of said orifices, and a valve means for controlling the rate of bypass flow, said valve means including a first valve element, a valve port formed in said first valve element and defining a portion of said bypass passage, and a second valve element registering with said first valve element and adapted to progressively restrict said port upon movement thereof in one direction relative to said first valve element, one side of said second valve element being exposed to the fuel pressure intermediate said orifice whereby it is urged toward a port closing position.

3. In a liquid fuel metering system for an internal combustion engine having an intake gas manifold and a plurality of engine cylinders, a separate manifold portion communicating with each engine cylinder, and a liquid fuel nozzle mounted in each manifold portion, each of said nozzles being adapted to inject a combustible charge of fuel into its associated manifold portion; a fuel delivery passage means for supplying said nozzles with liquid fuel, a load sensor unit comprising a fuel metering orifice situated in and defining a part of said fuel delivery passage, a valve element registering with said orifice for variably restricting the same, a movable wall, said valve element being joined to said movable wall, and means for subjecting one side of said movable wall to the pressure existing in said intake manifold, said delivery passage means including a plurality of branch fuel delivery conduits extending from said metering unit on the downstream side of said orifice to said nozzles, a separate conduit communicating with each nozzle.

4. In a liquid fuel metering system for an internal combustion engine having an intake gas manifold and a plurality of engine cylinders, a separate manifold portion communicating with each engine cylinder, and a liquid fuel nozzle mounted in each manifold portion, each of said nozzles being adapted to inject a combustible charge of fuel into its associated manifold portion; a fuel delivery passage means for supplying said nozzles with liquid fuel, a load sensor unit comprising a fuel metering orifice situated in and defining a part of said fuel delivery passage, 21 valve element registering with said orifice for variably restricting the same, a movable wall, said valve element being operatively associated and movable with said movable wall, a vacuum pressure passage extending from said load sensor to said intake manifold for subjecting one side of said movable Wall with the vacuum pressure existing in said intake manifold, said delivery passage means including a plurality of branch fuel delivery conduits extending from said metering unit on the downstream side of said orifice to said nozzles, a separate conduit communicating with each nozzle, said valve element being movable toward an orifice closing position upon an increase in intake manifold vacuum.

5. In a liquid fuel metering system for an internal combustion engine having an intake manifold and a 1'4 plurality of engine cylinders, a separate manifold portion communicating with each engine cylinder, a liquid fuel nozzle mounted in each manifold portion, each of' said nozzles being adapted to inject a combustible charge of fuel into its associated manifold portion, and a throttle valve mounted in each manifold on the downstream side of the associated nozzle; a fuel delivery passage means for supplying said nozzles with liquid fuel, a load sensor unit comprising a fuel metering orifice situated in and defining a part of said fuel delivery passage, a valve element registering with said orifice for variably restricting the same, a movable wall, said valve element being operatively associated and movable with said movable wall, a vacuum conduit extending from said load sensor to said intake manifold on the downstream side of said throttle valves to accommodate the transfer of a vacuum signal to one side of said movable wall.

6. In a liquid fuel metering system for an internal combustion engine having an intake manifold and a plurality of engine cylinders, a separate manifold portion communicating with each engine cylinder, a liquid fuel nozzle mounted in each manifold portion, each of said nozzles being adapted to inject a combustible charge of fuel into its associated manifold portion, and a throttle valve mounted in each manifold on the downstream side of the associated nozzle; a fuel delivery passage means for supplying said nozzles with liquid fuel, a load sensor unit comprising a fuel metering orifice situated in and defining a part of said fuel delivery passage, a valve element registering with said orifice for variably restrictmg the same, a movable wall, said valve element being operatively associated and movable with said movable wall, a vacuum conduit extending from said load sensor to said intake manifold on the downstream side of said throttle valves to accommodate the transfer of a vacuum signal to one side of said movable wall, said delivery passage means including a plurality of branch fuel delivery conduits extending from said metering unit on the downstream side of said orifice to said nozzles, a separate condult communicating with each nozzle.

7. The combination as set forth in claim 6 wherein said plurality of branch fuel delivery conduits communicates with said load sensor at a common location. 8. In a low pressure liquid fuel injection system for an internal combustion engine having a plurality of engine cylinders and an intake manifold with portions communlcatlng With each engine cylinder, a liquid fuel nozzle mounted in said manifold for supplying the latter w1th a combustible charge, a fuel delivery conduit communlcating with said nozzle, a load sensor unit and a speed sensor unit interposed in said fuel delivery conduit, each of said sensor units including a valve opening definmg a part of said conduit, said orifices being situated in series with the load sensor orifice being downstream from the speed sensor orifice, a fuel pump in said delivery conduit for creating a delivery pressure, separate metering valves registering with each of said valve openlugs for progressively restricting the same, speed responslve means for adjustably positioning said speed sensor metering valve with respect to its associated orifice, engme load responsive means for adjustably positioning said load sensor metering valve with respect to the load sensor orifice, a bypass passage extending from said fuel delivery conduit at a location intermediate said orifices to the intake side of said pump, and a flow control valve means situated in said bypass passage for varying the rate of bypass flow as determined by the magnitude of the fuel delivery pressure on the downstream side of said speed sensor orifice.

9. In a low pressure liquid fuel injection system for an internal combustion engine having an intake manifold and a plurality of engine cylinders, separate manifold portions extending to each engine cylinder, a liquid fuel nozzle mounted in each manifold portion, fuel delivery conduit means communicating with said nozzles, a fuel pump in said delivery conduit means for creating a fuel delivery pressure, a speed sensor unit and a load sensor unit disposed in said delivery conduit, each of said sensor units including a valve opening defining a part of said conduit means, a first valve element registering with the speed sensor valve opening, a second valve element registering with the load sensor valve opening, speed responsive means for adjustably positioning said first valve element, engine load sensitive means for adjustably positioning said second valve element, a collecting chamber situated on the downstream side of said loadsensor valve opening, and a plurality of branch conduits extending to said nozzles from said collecting chamber, one branch conduit communicating with each nozzle, said branch conduits communicating with said collecting chamber at locations which are substantially equidistant from said load sensor valve opening.

10. In a low pressure liquid fuel injection system for an internal combustion engine having an intake manifold and a plurality of engine cylinders, separate manifold portions extending to each engine cylinder, a liquid fuel nozzle mounted in each manifold portion, fuel delivery conduit means communicating with said nozzles, a fuel pump in said delivery conduit means for creating a fuel delivery pressure, a speed sensor unit and a load sensor unit disposed in said delivery conduit, each of said sensor units including a valve opening defining a part of said conduit means, a first valve element registering with the speed sensor valve opening, a second valve element registering with the load sensor valve opening, speed responsive means for adjustably positioning said first valve element, engine load sensitive means for adjustably positioning said second valve element, a collecting chamber situated on the downstream side of said load sensor valve opening, and a plurality of branch conduits extending to said nozzles from said collecting chamber, one branch conduit communicating with each nozzle, said branch conduits communicating with said collecting chamber at locations which are substantially equidistant from said load sensor valve opening, and a bypass conduit extending from said delivery conduit means at a point intermediate said valve openings to the intake side of said pump. I

11. The combination as set forth in claim 10 wherein said speed sensor includes a movable wall, said speed sensor metering valve being operatively associated and movable with said movable wall, a fuel chamber partly defined by said movable wall on each side thereof, one of said fuel chambers communicating with the downstream side of the speed sensor valve opening and the P ,v ing parameter of said combustion apparatus, a second fuel fuel metering means in said passage responsive to one 1.;

operating parameter of said combustion apparatus, a second fuel metering means in said passage responsive to another operating parameter of said combustion apparatus, fuel delivery means having a fuel delivery side connected with said passage for delivering fuel thereto and also having a fuel inlet side, and bypass means arranged to conduct a portion of the fuel metered by said metering means in said passage in series with said first fuel metering means and responsive to another operating parameter of said combustion apparatus, fuel delivery means having a fuel delivery side connected with said passage for delivering fuel thereto and also having a fuel inlet side, and bypass means extending from between said two fuel metering means to said inlet side of said fuel delivery means for conducting a portion of the fuel metered by said first fuel metering means to said inlet side, thereby to limit the fuel flow through said second metering means to a value equal to the difference between the flow metered by said first metering means and said portion of said metered flow.

14. A fuel metering system as in claim 13 and comprising an additional valve means in said bypass means responsive to the fuel pressure in said delivery passage at a point between said two fuel metering means to restrict said portion of said metered flow as a direct function of said pressure.

15. A liquid fuel metering system for an internal combustion engine comprising a fuel delivery passage, two fuel metering means arranged in series in said passage, means responsive to the speed of said engine for regulating one of said fuel metering means, means responsive to the load on said engine for regulating the other of said fuel metering means, fuel delivery means having a fuel delivery side connected with said passage on the upstream side of said two metering means for delivering fuel thereto and also having a fuel inlet side, bypass means extending from between said two fuel metering means to said inlet side of said fuel delivery means for conducting a portion of the fuel metered by the first of said metering means in series to said inlet side, thereby to limit the fuel flow through the second of said metering means to a value equal to the diiference between the flow metered by said first means and said portion of said metered flow, and valve means in said bypass means responsive to the fuel pressure in said delivery passage between said two fuel metering means to restrict said portion of said metered flow as a direct function of said pressure.

References Cited in the'file of this patent UNITED STATES PATENTS 2,281,411 Campbell Apr. 28, 1942 2,447,261 Mock Apr. 17, 1948 2,468,416 Stresen-Reuter Apr. 26, 1949 2,623,509 Gold et al Dec. 30, 1952 2,636,553 Ballantyne et al. Apr. 28, 1953 2,688,841 Decher et a1 Sept. 14, 1954 2,772,668 Nystrom et al Dec. 4, 1956 UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 2,871,844 February 3, 1959 Clifton M. Elliott et a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3,, line 65, for "sponsor" read SGIISIOI column 5, line 54, for "housinllg' read housing column 9 line 53, for "thereof" read he therefore Signed and sealed this 23rd day of June 1959.

SEAL) ttest:

\RL Ii. AXLINE ROBERT C. WATSON testing Officer Commissioner of Patents 

